A temporal DBMS is said to be history-oriented if:
- It supports history-unique identification (e.g., via
time-invariant keys, surrogates, or OIDs);
- The integrity of histories is inherent in the model, in the
sense that history-related integrity constraints might be enforced
and the language provides a mechanism (history variables and
quantification) for direct reference to histories;
- The DML allows easy manipulation of histories, in the sense that
the language provides for user-friendly history selection, history
retrieval and history modification primitives.